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Monali N Basutkar, Saumil Samant, Joseph Strzalka, Kevin G Yager, Gurpreet Singh, Alamgir Karim
Template-free directed self-assembly of ultrathin (~10's nm) lamellar block copolymer (l-BCP) films of high-interfacial area into vertically oriented nanodomains holds much technological relevance for fabrication of next-generation devices from nanoelectronics to nanomembranes due to domain interconnectivity and high interfacial area. We report for the first time, the formation of full thru-thickness vertically oriented lamellar domains in 100 nm thin polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films on quartz substrate, achieved without any PMMA-block wetting layer formation, quartz surface modification (templating chemical, topographical) or system modifications (added surfactant, top-layer coat)...
November 14, 2017: Nano Letters
Ibon Alkorta, Joseph C R Thacker, Paul L A Popelier
The quantum chemical topology method has been used to analyze the energetic profiles in the X(-)  + CH3 X → XCH3  + X(-) SN 2 reactions, with X = F, Cl, Br, and I. The evolution of the electron density properties at the BCPs along the reaction coordinate has been analysed. The interacting quantum atoms (IQA) method has been used to evaluate the intra-atomic and interatomic energy variations along the reaction path. The different energetic terms have been examined by the relative energy gradient method and the ANANKE program, which enables automatic and unbiased IQA analysis...
November 10, 2017: Journal of Computational Chemistry
Elsie Rizk, Allison D Wilson, Michelle U Murillo, David R Putney, Bcps-Aq Cardiology
BACKGROUND: Vascular surgery patients often require anticoagulation with intravenous unfractionated heparin monitored via anti-Xa levels or the activated partial thromboplastin time (aPTT). This study compares the two monitoring strategies in terms of major bleeding events in the vascular surgery population. METHODS: This was a single center, retrospective study that included patients treated with a pharmacy-managed heparin protocol monitored by either anti-Xa or aPTT after vascular surgery...
November 8, 2017: Therapeutic Drug Monitoring
Aswathy Joseph, Vibin Ipe Thomas, Gaweł Żyła, Padmanabhan Sridharan Alapat, Suresh Mathew
A comprehensive study on the structure, nature of interaction and properties of six ionic pairs of 1-butylpyridinium and 1-butyl-4-methylpyridinium cations in combination with tetrafluoroborate (BF4-), chloride (Cl-) and bromide (Br-) anions have been carried out using Density Functional Theory (DFT). The anion-cation interaction energy (ΔEint), theoretical band gap, molecular orbital energy-order, DFT-based chemical activity descriptors: chemical potential (μ), chemical hardness (η) and electrophilicity index (ω) and distribution of density of states (DOS) of these ion-pairs were investigated...
November 7, 2017: Journal of Physical Chemistry. A
Manesh Gopinadhan, Youngwoo Choo, Kohsuke Kawabata, Gilad Kaufman, Xunda Feng, Xiaojun Di, Yekaterina Rokhlenko, Lalit H Mahajan, Dennis Ndaya, Rajeswari M Kasi, Chinedum O Osuji
The interaction of fields with condensed matter during phase transitions produces a rich variety of physical phenomena. Self-assembly of liquid crystalline block copolymers (LC BCPs) in the presence of a magnetic field, for example, can result in highly oriented microstructures due to the LC BCP's anisotropic magnetic susceptibility. We show that such oriented mesophases can be produced using low-intensity fields (<0.5 T) that are accessible using permanent magnets, in contrast to the high fields (>4 T) and superconducting magnets required to date...
October 23, 2017: Proceedings of the National Academy of Sciences of the United States of America
Qing Peng, Yu-Chih Tseng, Yun Long, Anil U Mane, Shane DiDona, Seth B Darling, Jeffrey W Elam
There are broad interests in selective and localized synthesis in nanodomains of self-assembled block copolymers (BCPs) for a variety of applications. Sequential infiltration synthesis (SIS) shows promise to selectively grow a controllable amount of materials in one type of nanodomain of a self-assembled BCP film. However, the effects of nanostructured domains in a BCP film and SIS cycles on the material growth behavior of SIS are rarely studied. In this work, we investigated the growth behavior of TiO2 SIS within self-assembled polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films and the two corresponding pure homopolymer films (PS and PMMA) by using in situ quartz crystal microbalance (QCM)...
November 7, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Cian Cummins, Alan P Bell, Michael A Morris
The prolonged and aggressive nature of scaling to augment the performance of silicon integrated circuits (ICs) and the technical challenges and costs associated with this has led to the study of alternative materials that can use processing schemes analogous to semiconductor manufacturing. We examine the status of recent efforts to develop active device elements using nontraditional lithography in this article, with a specific focus on block copolymer (BCP) feature patterning. An elegant route is demonstrated using directed self-assembly (DSA) of BCPs for the fabrication of aligned tungsten trioxide (WO₃) nanowires towards nanoelectronic device application...
September 30, 2017: Nanomaterials
I Otsuka, N Nilsson, D B Suyatin, I Maximov, R Borsali
Self-assembly of block copolymers (BCPs) provides an attractive nanolithography approach, which looks especially promising for fabrication of regular structures with characteristic sizes below 10 nm. Nevertheless, directed self-assembly (DSA) and pattern transfer for BCPs with such small features remain to be a challenge. Here we demonstrate DSA of the maltoheptaose-block-polystyrene (MH1,2k-b-PS4,5k) BCP system using graphoepitaxy. BCP thin films were self-organized by solvent vapor annealing in tetrahydrofuran (THF) and water into sub-10 nm scale cylinders of the maltoheptaose (MH) block oriented horizontally or perpendicularly to the surface in a polystyrene (PS) matrix...
October 18, 2017: Soft Matter
Jaewon Choi, Ilja Gunkel, Yinyong Li, Zhiwei Sun, Feng Liu, Hyeyoung Kim, Kenneth R Carter, Thomas P Russell
A simple and robust method has been developed for the generation of macroscopically ordered hexagonal arrays from the directed self-assembly (DSA) of cylinder-forming block copolymers (BCPs) based on minimal trench patterns with solvent vapor annealing. The use of minimal trench patterns allows us to probe the guided hexagonal arrays of cylindrical microdomains using grazing incidence small angle X-ray scattering (GISAXS), where the sample stage is rotated on the basis of the six-fold symmetry of a hexagonal system...
October 12, 2017: Nanoscale
Samiyara Begum, Ranga Subramanian
Different isomers of the valence isoelectronic pairs of the heterodimers N2O-SCS and N2O-OCS were investigated using MP2 and CCSD(T) methods with the aug-cc-pVXZ (X = D, T) basis set with anharmonic frequency calculations. Interaction energies of both the heterodimers were estimated at the CBS limit and for CCSD(T)/aug-cc-pVTZ. One isomer was located for the N2O-SCS heterodimer. In the case of the N2O-OCS heterodimer, three planar slipped-parallel isomers were characterized. There was no significant change in electron density at the bond critical points (BCPs) of various intra-bonds but the presence of inter-bonds with a weak electron density at the BCPs in the complexes was found as per the results from the quantum theory of atoms in molecules (QTAIM) analysis...
October 4, 2017: Physical Chemistry Chemical Physics: PCCP
Abolfazl Azizi, Ali Ebrahimi
The interaction between positively charged aromatic groups (π(+)-π(+)) is characterized by stacked pyridinium ion derivatives X-PyH(+)||X-PyH(+) (XH, NH2, OH, CN, F, Br and Cl) at the M06-2X/6-311++G(d,p) level of theory in the presence of three solvents. The results indicate the formation of π(+)-π(+) stacking in a dielectric solvent can be due to the significant stability of the charge-charge repulsion forces. The trend in the absolute value of stacking interaction energy |ΔEπ(+)⋯π(+)| with respect to the solvent is formamide>water>acetone...
September 4, 2017: Journal of Molecular Graphics & Modelling
Yuqing Wu, Ke Wang, Haiying Tan, Jiangping Xu, Jintao Zhu
A simple yet efficient method is developed to manipulate the self-assembly of pH-sensitive block copolymers (BCPs) confined in emulsion droplets. Addition of acid induces significant variation in morphological transition (e.g., structure and surface composition changes) of the polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) assemblies, due to the hydrophobic-hydrophilic transition of the pH-sensitive P4VP block via protonation. In the case of pH > pKa(P4VP) (pKa (P4VP) = 4.8), the BCPs can self-assemble into pupa-like particles because of the nearly neutral wetting of PS and P4VP blocks at the oil/water interface...
September 6, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Weichang Li, Siqi Liu, Hang Yao, Guoxing Liao, Ziwei Si, Xiangjun Gong, Li Ren, Linge Wang
Polymer vesicles are self-assembled shells of amphiphilic block copolymers (BCPs) that have attracted tremendous interest due to their encapsulation ability and intracellular delivery of therapeutic agents. However, typical processes for the formation of polymer vesicles lead to ensembles of structures with a broad size distribution (from nanometer to micrometer scale) which result in a limitation for efficient cellular uptake. In this study, we present a simple and efficient approach for the fabrication of polymer vesicles with uniform nanoscale dimensions from template formation of electrosprayed particles in a high throughput manner...
August 16, 2017: Journal of Colloid and Interface Science
Finizia Auriemma, Claudio De Rosa, Anna Malafronte, Rocco Di Girolamo, Chiara Santillo, Yuri Gerelli, Giovanna Fragneto, Robert Barker, Vincenzo Pavone, Ornella Maglio, Angela Lombardi
We set up a facile approach for fabrication of supports with tailored nanoporosity for immobilization of enzymes. To this aim block copolymers (BCPs) self-assembly has been used to prepare nanostructured thin films with well-defined architecture containing pores of tailorable size delimited by walls with tailorable degree of hydrophilicity. In particular, we employed a mixture of polystyrene-block-poly(l-lactide) (PS-PLLA) and polystyrene-block-poly(ethylene oxide) (PS-PEO) diblock copolymers to generate thin films with a lamellar morphology consisting of PS lamellar domains alternating with mixed PEO/PLLA blocks lamellar domains...
August 30, 2017: ACS Applied Materials & Interfaces
Xiao-Xiao Lu, Yi-Fan Jiang, Hong Li, Ying-Ye Ou, Zhi-De Zhang, Hong-Ye DI, Dao-Feng Chen, Yun-Yi Zhang
Lipopolysaccharides (LPS) contamination in herbal crude polysaccharides is inevitable. The present study was performed to explore the effect of polymyxin B on abolishing the influence of LPS contamination in mononuclear cells. LPS was pretreated with polymyxin B sulfate (PB) at different concentrations for 1, 5 or 24 h, and then used to stimulate RAW264.7 and mouse peritoneal macrophages (MPMs). The nitric oxide (NO) and tumor necrosis factor-α (TNF-α) in cell culture supernatant, as the indications of cell response, were assayed...
July 2017: Chinese Journal of Natural Medicines
Yan Zhang, Yun He, Nan Yan, Yutian Zhu, Yuexin Hu
Recently, it has been reported that the incorporation of functional inorganic nanoparticles (NPs) into the three-dimensional (3D) confined self-assembly of block copolymers (BCPs) creates the unique nanostructured hybrid composites, which can not only introduce new functions to BCPs but also induce some interesting morphological transitions of BCPs. In the current study, we systematically investigate the cooperative self-assembly of a series of size-controlled and surface chemistry-tunable gold nanoparticles (AuNPs) and polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer within the emulsion droplets...
August 28, 2017: Journal of Physical Chemistry. B
Yanhua Sun, Shian Zhong
In this work, a novel strategy was developed for the selective recognition of protein based on oil-in-water Pickering emulsions-hydrogels polymerization and interfacial imprinting method. For the first time, nanoscale trifunctional bovine hemoglobin (BHb) played three roles simultaneously during the process, including emulsifier, template protein and sacrificial material for further exposing recognition sites. Prior to acting as stabilizers, bovine hemoglobin colloidal particles (BCPs) were firstly prepared by acidification and heat denaturation...
July 29, 2017: Colloids and Surfaces. B, Biointerfaces
Emmanuel Aubert, Enrique Espinosa, Irène Nicolas, Olivier Jeannin, Marc Fourmigué
We compare here the halogen bond characteristics of bimolecular adducts involving either N-bromo- or N-iodosaccharin as strong halogen bond donors, with 4-picoline as a common XB acceptor. In the NBSac·Pic system, the bromine atom of NBSac is displaced toward the picoline, almost at a median position between the two nitrogen atoms, NSac and N'Pic, with NSacBr and BrN'Pic distances at 2.073(6) and 2.098(6) Å respectively. This extreme situation contrasts with the analogous iodine derivative, NISac·Pic, where the NSac-I and IN'Pic distances amount to 2...
October 13, 2017: Faraday Discussions
Johanna Zessin, Franziska Fischer, Andreas Heerwig, Alfred Kick, Susanne Boye, Manfred Stamm, Anton Kiriy, Michael Mertig
A novel approach for the integration of π-conjugated polymers (CPs) into DNA-based nanostructures is presented. Using the controlled Kumada catalyst-transfer polycondensation, well-defined thiophene-based polymers with controllable molecular weight, specific end groups, and water-soluble oligoethylene glycol-based side chains were synthesized. The end groups were used for the easy but highly efficient click chemistry-based attachment of end-functionalized oligodeoxynucleotides (ODNs) with predesigned sequences...
July 27, 2017: Nano Letters
Ana Teresa Limon-Miro, Veronica Lopez-Teros, Humberto Astiazaran-Garcia
Current dietary guidelines for breast cancer patients (BCPs) fail to address adequate dietary intakes of macro- and micronutrients that may improve patients' nutritional status. This review includes information from the PubMed and Biomed Central databases over the last 15 y concerning dietary guidelines for BCPs and the potential impact of a personalized, nutrient-specific diet on patients' nutritional status during and after antineoplastic treatment. Results indicated that BCPs should receive a nutritional assessment immediately after diagnosis...
July 2017: Advances in Nutrition
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